It is currently desirable to increase the operational speed of circular knitting machines and this results in the knitting needles being subjected to greater impact forces. When the operating speed of the circular knitting machine is increased, the speed of movement in a vertical direction increases as the needles are raised and lowered in the knitting operation. This increased vertical speed also increases the inertia that is generated at the upper and lower ends of the vertical movements of the needle so that high impact forces or shock are transmitted from the cams to the needle butts and to the needle hooks through the needle shank, thereby leading to an increased incidence of hook and/or butt breakage and wear. In certain cases, this increased inertia will cause the needle butts to deviate from the cam track and cause additional damage to the needles. It has been proposed that the weight of the needle be reduced to decrease the impact force and shock transmitted from the butts to the hooks; for example, U.S. Pat. Nos. 3,464,237 and 4,452,053 disclose stamped latch needles with cutouts spaced along the back edge of the needle to provide shock absorbing bridges positioned between the butt and hook. It is also known to provide cutouts in the form of slots, extending through the shank and/or butt of the needle to provide an anti-shock construction. Japanese Patent No. 1023328 (Publication No. SHO 55-9103) discloses a stamped needle in which a portion of the shank between the butt and the hook is provided with a circular configuration having substantially the same diameter as the width of the shank and with a central hole extending through the shank. This circular section of the shank reduces the weight of the needle and tends to reduce the transmittal of the impact forces from the butt to the hook.
While the various cutouts provided in the shank of needles have permitted increased operational speed of the circular knitting machines, these cutouts tend to limit the strength of the needle shank and must be limited to certain critical dimensions or the shank is weakened to the point that breakage of the shank may occur at high operating speeds.